The present invention relates generally to the field of audio control and in particular to a vehicle audio integrator.
In 2003, over 24 million trucks in the U.S. hauled over 9 billion tons of freight, logging 444.4 billion miles. Of those, over 2.6 million were class 8 trucks (weighing more than 33,000 pounds—typically, “18-wheelers”), which logged 114.1 billion miles. Accurate scheduling and real-time tracking of class 8 trucks is increasingly important to the trucking industry and its customers. For example, the “just in time” inventory model that allows factories and retailers to virtually eliminate large inventories, and accordingly, to dramatically cut operating costs, depends heavily on accurate and timely delivery of raw materials, parts, and goods, much of which are shipped by trucks.
Satellite-based vehicle communication systems have been deployed in class 8 trucks, as well as other vehicles, for years, to aid dispatchers in scheduling and tracking trucks en route. These systems provide communications between truckers and dispatchers in remote areas, where terrestrial wireless communication systems are not widely deployed, and provide at least rough estimates of the truck's geographic location. More modern vehicle communication and tracking systems include Global Positioning Satellite (GPS) receiver functionality, providing highly accurate vehicle location information. With the development and deployment of increasingly accurate geographic databases, the vehicle location systems may automatically provide real-time, turn-by-turn directions to guide drivers along predetermined routes. As well known in the art, a route comprises a plurality of predetermined waypoints, each waypoint corresponding to a specific geographic coordinate. The navigation system compares the truck's current location to the next waypoint, issuing prompts or directions as the truck approaches waypoints of interest, such as freeway exits, intersections, delivery addresses, and the like.
For safety, such turn-by-turn directions are preferably delivered audibly, such as by pre-recorded or computer-synthesized voice messages. The latter option additionally allows the system to “read” text messages, such as the Short Message Service (SMS) or “texting” offered by many cellular phone services, or e-mail, to the driver. Also, to further increase safety by minimizing diversion of the driver's attention from the task of driving the rig, these systems may now, or in the near future, include voice recognition functionality, allowing the driver to set parameters, request information, call up queued messages, and the like, via voice commands.
In creating systems that deliver information to the driver via synthesized voice and accept commands from the driver via voice recognition, designers have been forced to deal with the reality of the audio environment in a truck cab. Typically, class 8 trucks include a variety of independent audio devices, such as an in-dash AM/FM radio, tape player, CD player, or the like; a Citizens Band (CB) radio (in 2003, 28% of trucks still utilized CB radios); and personal audio sources, such as a cellular telephone equipped with a hands-free interface, MP3 music player, satellite radio receiver, and the like. Each of these audio devices has its own on-off and volume controls (as well as channel selection and other control inputs) that must be manually adjusted by the driver. Additionally, some of the audio sources have their own speakers, giving rise to widely varying audio quality, while others may access the high-fidelity speakers built into the cab through the in-dash stereo (i.e., the MP3 player may interface to the stereo through a cassette tape interface or FM modulator).
In actual use, this cluttered audio environment presents numerous problems. For example, a driver engaged in a cell phone conversation or listening to music may miss a directional instruction from the vehicle navigation system. In response, the trucker can pause the conversation or reduce the volume of the radio, and request that the directional instruction be repeated. However, a real-time message coming over the CB radio is simply lost. Furthermore, while noise-cancelling microphones and voice recognition system training can reduce or eliminate the deleterious effects of much ambient noise (such as wind, road, and engine noise), the system cannot be trained to “ignore,” e.g., a voice coming in over the CB radio in the middle of a trucker's voice command. Recognition accuracy suffers so badly in the presence of multiple voices that the command will not be recognized. However, the trucker may not wish to turn off the CB radio just to give commands to the navigation system.
Some forms of simple, priority-based audio integration are known in the art, for example, those found in general aviation radios and headsets. Both intercom and radio voice communications are routed to an aviation headset, which may include an audio input for a portable satellite radio receiver, MP3 player, or the like. The system prioritizes communication channels, and switches in higher priority channels as they become active (as detected by, e.g., a squelch circuit). For example, music may be interrupted by activity on a low-priority radio channel (e.g., reporting weather or other routine information), which in turn may be interrupted by activity on a high-priority radio channel (e.g. tuned to an air traffic control frequency), which in turn may be interrupted by intercom communications. The switching between audio sources is abrupt, and the pilot may have to monitor a new audio stream for several moments to identify its source. Furthermore, the beginning of messages spoken immediately upon keying a microphone may be lost in the time required for the squelch circuit and audio switching circuit to route the new, high-priority audio to the headset speakers.